1. Field of the Invention
The present invention is an inertia sensitive device, such as may be used for detecting motion as part of an alarm system or for reacting to impact.
It is known to use piezoelectric sensors to detect unwanted motion, for example vibrations caused by the presence of an intruder or by unauthorised removal of equipment associated with the sensor. Highly sensitive sensors of this type have been developed, to the extent that very small vibrations caused by an intruder at some distance from the device may readily be detected. However a major disadvantage of such devices is that, because of their sensitivity, they also react to vibrations which are a consequence of acceptable events or conditions. Such reactions are at best a nuisance and may at worst devalue the significance of an important alarm signal, with possibly serious consequences.